Glenn,
1. Open ArchiCAD
2. Go to Document/Layout Book/New Master Layout
3. Set the dimensions of the page, name of the layout and margins. Ignore the rest of the settings here for now.
4. Open OSX Finder (Mac) or Windows Explorer (Windows) and browse to your DWG file.
5. Drag the DWG file onto the layout page you created in step 3.
6. Edit as needed and save.
Now when you make a new layout you can choose the master you just created to use as your title block.
Master Layout
DWG Import (See drag & drop section)